With Mike B's blessing, I will be soon releasing the complete files for the 9Xtreme to the public domain so customers can better repair damaged units or build a new one.

I intended to already have this done, but I've been busy with other things. I'm putting this post here as a placeholder and I will update it once I've packaged everything up and ready for download.

[update Sept 26, 2017] I've attached a PDF of the Schematic.
[update Feb 1, 2018] I've attached a zip file containing two files: 9Xtreme_1.1.dch which is a schematic file and 9Xtreme_1.1.dip which is a board layout file. Both of these are for the program DipTrace.

I have a feeling BangGood will pick it up. Not sure whether it's good or bad, but there is some demand for M9 3V3 gimbals on the 9x and 9Xtreme seems to be a perfect open, although it's no longer produced nor sold.
Luckily I was an early adopter and still cherish my board

Just had a quick look, and I can spot the little mistake that leaves the board unprotected in case of reversed battery polarity, hence the need to solder a diode on the switch board.
As far as I understand (someone correct me if I'm wrong), on the connector "J4", Pin 2 (Battery) should be connected between Q3 (which is the reverse polarity protection) and Q1.
The way it is now, Q3 is left out of the circuit when the Power switch is ON, not protecting the board..

I'm mentioning this so people understand why the diode on the switch board is a must have thing, and also, if someone decides to make a board, at least it can be corrected.

Also, on "J6" pin 7 it should be PXX-PPM1 instead of PXX-PPM2, and on "U2" Pin 2 Should be PXX-PPM2 instead of PXX-PPM1. They seem to be swapped..

Another thing, if someone builds this board, Place a 100 ohm resistor in series with PXX-PPM1 and another 100 ohm resistor in series with PXX-PPM2. There were a number of boards that got damaged because of some higher voltage being fed to the processor pins, probably caused by inserting /removing the RF module with the radio powered ON.

Schematic attached to the original post. What do people want? Bill of materials? Layout files? I used Diptrace to make them but I don't think very many people use that. Most people seem to use Eagle.

Steven, I am new to the forum but I have been trying to get my hands on a 9xtreme board for over a year. I am thrilled to see that you've posted the schematic. Look forward to getting a layout so I can build my own. Thank you!

However, I used a program that most of you are probably not familiar with. I know most hobbyists use Eagle, but I've never been fond of it. My preference is DipTrace. It does have a free version, but it is limited to 300 pins and this project is well beyond that. There is a free TRIAL as well, which doesn't have the pin limitations, but is only good for 30 days.

I would export to Eagle, but there doesn't seem to be a function for that (It can import but not export). I can provide the Gerber files, but they aren't editable. Although, you'd be able to send those to a place like oshpark (highly recommended!) and get boards sent to you that meet all the specifications of the original 9Xtreme. I can also post the Bill of Materials. I'm going to package all that up and post that as well.

[edit] I've attached them here, since I can't add them to the original post.